The exploration of oil and gas may involve the investigation of geological formations to locate subsurface reservoirs. Seismic surveys may be performed to gather data and/or generate images of geological formations at locations of interest. To generate the seismic surveys, a seismic source, such as a seismic vibrator or other surface or sub-surface energy source, may be used to generate acoustic waves through the geological formations. For example, a vibroseis system may include a truck with a base plate that may be lowered to the ground and a reaction mass driven by a hydraulic system to generate the acoustic waves. A receiver may be provided to measure the acoustic waves as they rebound from the geological formations. Examples of seismic vibrators are described in U.S. Pat. Nos. 4,664,223 and 4,184,144. The measurements captured by the receiver may be analyzed to determine geological parameters and/or to generate two and/or three dimensional depictions of geological formations. This information may be used, for example, to analyze potential oil fields and/or to design well plans for producing hydrocarbons or other resources from the geological formations.
During operation, seismic vibrators may generate significant amounts of harmonic energy. Such harmonic energy may affect the signals generated by the seismic vibrators, thereby affecting measurements. Techniques have been developed to measure the ground force generated by a seismic vibrator, as described, for example, in U.S. Pat. No. 4,664,223 and in Shan et al, “Load Cell System Test Experience: Measuring the Vibrator Ground Force on Land Seismic Acquisition,” SEG Houston 2009 Int'l Exposition and Annual Meeting. Ground force measurements may be analyzed to make use of harmonic energy and enhance, for example, bandwidth of signals of the seismic vibrator.
Despite the development of advanced techniques for measuring certain seismic parameters, such as ground force, there remains a need to provide enhanced seismic measurement capabilities and/or advanced techniques for further enhancing seismic operations. The present invention is directed to fulfilling these needs in the art.